Measurement and implications of the distance between the sphenopalatine ganglion and nasal mucosa: a neuroimaging study

• Published in: Journal of headache and pain Vol. 19; no. 1; pp. 14 - 10
• Main Authors: Crespi, Joan, Bratbak, Daniel, Dodick, David, Matharu, Manjit, Jamtøy, Kent Are, Aschehoug, Irina, Tronvik, Erling
• Format: Journal Article
• Language: English
• Published: Milan Springer Milan 13.02.2018; Springer Nature B.V; BMC
• Subjects: Administration, Intranasal; Adult; Aged; Analysis of Variance; Anesthetics, Local - administration & dosage; Block; Connective tissues; Female; Ganglia; Headache Disorders - drug therapy; Humans; Internal Medicine; Intranasal; Intranasal administration; Local anaesthetics; Local anesthesia; Magnetic resonance imaging; Male; Medicine; Medicine & Public Health; Middle Aged; Migraine Disorders - drug therapy; Mucosa; Nasal Mucosa - anatomy & histology; Nasal Mucosa - diagnostic imaging; Neuroimaging; Neuroimaging - methods; Neurology; Nose; Pain Medicine; Pterygopalatine Fossa - anatomy & histology; Pterygopalatine Fossa - diagnostic imaging; Pterygopalatine ganglion; Research Article; Sphenopalatine ganglion; Sphenopalatine Ganglion Block - methods; Topical application; Sphenopalatine ganglion; Block; Intranasal; Local anaesthetics; Pterygopalatine ganglion
• ISSN: 1129-2369; 1129-2377; 1129-2377
• DOI: 10.1186/s10194-018-0843-5

Background Historical reports describe the sphenopalatine ganglion (SPG) as positioned directly under the nasal mucosa. This is the basis for the topical intranasal administration of local anaesthetic (LA) towards the sphenopalatine foramen (SPF) which is hypothesized to diffuse a distance as short as 1 mm. Nonetheless, the SPG is located in the sphenopalatine fossa, encapsulated in connective tissue, surrounded by fat tissue and separated from the nasal cavity by a bony wall. The sphenopalatine fossa communicates with the nasal cavity through the SPF, which contains neurovascular structures packed with connective tissue and is covered by mucosa in the nasal cavity. Endoscopically the SPF does not appear open. It has hitherto not been demonstrated that LA reaches the SPG using this approach. Methods Our group has previously identified the SPG on 3 T–MRI images merged with CT. This enabled us to measure the distance from the SPG to the nasal mucosa covering the SPF in 20 Caucasian subjects on both sides ( n  = 40 ganglia). This distance was measured by two physicians. Interobserver variability was evaluated using the intraclass correlation coefficient (ICC). Results The mean distance from the SPG to the closest point of the nasal cavity directly over the mucosa covering the SPF was 6.77 mm (SD 1.75; range, 4.00–11.60). The interobserver variability was excellent (ICC 0.978; 95% CI: 0.939–0.990, p  < 0.001). Conclusions The distance between the SPG and nasal mucosa over the SPF is longer than previously assumed. These results challenge the assumption that the intranasal topical application of LA close to the SPF can passively diffuse to the SPG.